auto box problem

my rr will drive if i go into 1st 2nd and 3rd then in drive it will then go up and down without problems unless i slow to below 10mph but if i go stright into drive it just revs any one have any ideas
thanks

Sounds like a transmission that uses a sprag (one-way clutch) to react 1st gear but has a by-pass clutch for overrun braking when you select it 'manually'. The sprag is knackered so the engine just revs like it's in neutral when you select 'D' but when you select '1' the clutch engages and overrides the sprag.
What model is it?

sorry not sure what model it is are there any tel tel signs on the box in situ

Have a look under FAQS on the Ashcroft transmissions websites, I have become well aquainted with it since trouble with my auto.

english111 said:

sorry not sure what model it is are there any tel tel signs on the box in situ

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Sorry, I meant your Range Rover. Is it a Classic, P38 or L322? Petrol or Diesel?

ok it is a 1997 p38 diesel had a look on Ashcroft transmissions websites they say get a new one they are probably right but i can hope its only a silly thing like filter and oil as it is ok once it is going

I replaced the part and had many, many miles of trouble free motoring.....thought someone had dropped a tank next to me when it went though...pulling of at the t-lights....blimey!

Yes, sure enough, the 4HP22 does use a sprag clutch to react 1st gear in 'D' - numbered 15 in the diagram attached. Clutch 8 bypasses it when you engage '1'.
I shouldn't waste money on changing fluid & filters if I were you - your transmission needs a rebuild.

is there any differance between a gearbox fitted to a 4.6 and a gearbox fitted to a bmw engine

yep, ones a 4.6 box and the others a 2.5 box

The diesel & 4.0 petrol use the ZF 4HP22 transmission, the 4.6 uses the higher capacity ZF 4HP24. Petrol models have a larger torque converter than the diesel.

Bemble said:

The diesel & 4.0 petrol use the ZF 4HP22 transmission, the 4.6 uses the higher capacity ZF 4HP24. Petrol models have a larger torque converter than the diesel.

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According to RAVE, the 4HP24 box is slightly longer than the 4HP22